I just tested the playlist thing a few days ago.
1) Go into the main FH folder, look for music.cfg and open it.
2) Make a new group, without spaces, special signs and with a short name. Put it into a new row with braces around it, like this:
[newgroup]
3) Add you music. Put the music somewhere in your FH folder (perhaps the map's folder).
4) To add music, enter the file name with file extension and path. example:
media/terrains/NewMap/Music.mp3.
You can add as many as you want, every one in a new row below your groups name.
5) Open FH, go into mapmaker and enter the groups name (without the braces!) into the box.
It will shuffle the songs.
Hope this helps :3